In an image sensing apparatus such as a digital still camera, the output signal from an image sensing device such as a CCD sensor or CMOS sensor is subjected to an A/D conversion, the digital signal is subsequently subjected to various processing such as a white balance correction, JPEG compression is performed and the compressed data is recorded on a removable recording medium such as a memory card. Further, in a case where a sensed image is edited, generally this is performed by utilizing an image-editing application program that runs on a general-purpose information processing apparatus such as a personal computer.
JPEG compression is irreversible. Accordingly, the image (the decoded image) when it undergoes editing is different from the image that prevailed when it was sensed by the image sensing device and the nature of editing that can be applied naturally is limited. This is unsatisfactory for a user who possesses sophisticated editing know-how.
In this regard, there is prior art (e.g., see the specification of Japanese Patent Application Laid-Open No. 3-49483) applicable to an image sensing apparatus such as a digital still camera in which the output signal from the image sensing device is subjected to an A/D conversion, the resultant signal is subsequently subjected to reversible compression, based upon the TIFF format or a manufacturer-specific compression format, as digital image data (referred to as “raw image data” below) without being subjected to almost any image processing, and the raw image data, camera-specific attribute information (referred to as “image sensing device filter characteristics” below) signifying such characteristics of the color filter of the image sensing device as the pixel array, filter color array and sensitivity characteristic (spectral sensitivity, etc.) of each pixel, and photographic condition information that prevailed when the raw image data was captured are recorded in association with one another on a removable recording medium such as a memory card.
For example, in a case where processing is executed by a personal computer, raw image data is subjected to reproduction image processing (referred to as “development processing”) based upon image sensing conditions associated with the raw image data as attribute information thereof, and the raw image data that has been developed is displayed on a monitor or the like. The application program performs reproduction by executing image processing such as pixel-by-pixel interpolation processing conforming to the image sensing device filter characteristics, color separation processing, white balance processing conforming to light-source information prevailing at the time of image sensing, luminance adjustment processing conforming to such photographic conditions as exposure time, shutter speed and zoom position, color adjustment processing and sharpness processing. In a case where an image thus reproduced is observed and the user wishes to set the white balance or color adjustment at will, development processing is executed again from the raw image data based upon the attribute information and image processing parameters.
In general, however, unprocessed image data such as raw image data is large in quantity because the output signal from the image sensor is held as is as image information, and development processing for effecting a conversion to data that can be displayed on a monitor or the like by the above-described application software requires a long processing time since many image processing steps are executed. For this reason, the state of the image represented by raw image data is not known until development processing is completed, the user must wait until processing is finished and the image displayed and hence there are problems in terms of the display speed of development processing and in terms of usability. That is, when raw image data is displayed in the normal display mode in the prior art, the display is presented after development processing is applied to the raw image data of the raw image file, and if the mode is made a high-speed preview mode (JPEG preview mode) by a mode changeover, what is displayed is always JPEG data, which is image data that has undergone development processing and is created at the time of photography. However, the following problems arise:    1) When the user has specified a development parameter different from the setting (photographic condition parameter) that prevailed at the time of photography, in the JPEG preview mode the JPEG data indicative of the content of development processing at the time of photography is always displayed and therefore the result of image processing based upon the parameter designated by the user cannot be verified.]    2) In order to check the result of processing based upon the parameter that has been designated by the user, it is required that the user switch the mode of the display to the normal display mode each time, resulting in poor usability.